Sean Walberg’s blog

Linux Unwired

While Windows users have no problem using all the wireless gear out there, not everything is supported in Linux. Add to this the command line tools for dealing with wireless, and you have a recipe for confusion. “Linux Unwired” demystifies the Linux Wireless system, and provides guidance for purchasers to make sure that they buy the most supported equipment possible.

It should be noted early on that 802.11b is not the only thing covered in the book. The other variants (a and g) are there, in addition to IRDA (infrared), Bluetooth, and Data over Cellular. On the latter point, much of the content deals with US based providers, but it still provides a good backing on the subject for those of us outside the country.

802.11b is the main focus, taking up around half the book. It starts with a discussion of the chipsets behind the cards, and how the map to Linux support. Here is where the reader gets advice on which card to buy, or at least what to look out for when buying a card. One thing I found interesting was the WLAN driver loader, which is an inexpensive product that lets Linux load binary WLAN modules. Some cards are not supported enough in Linux to do things like WEP security, which is where this product comes in. Again, the book leads the reader around the situations when this is necessary and when it isn’t.

In addition to WEP, other methods of authentication are covered such as 802.1x authentication and 802.11i, the successor to WEP. It’s also a good example of the broad scope of the book and a focus on interoperability with existing systems, rather than assuming the reader is building everything from the ground up.

Access points take up two chapters, the first looking at how to use them with Linux. Before reading this book, I was under the impression that access points all used web browsers or telnet for configuration, but apparently some need Windows software. There are situations where people have developed software to emulate this functionality, and pointers are provided. The second of the two chapters is on building your own access point, which is a fascinating look at using micro-linux distributions and mini-x86 hardware to build access points with rich functionality (for those less adventurous or well funded, the same can be done with any old hardware). There is also a look at soldering on a serial port to a popular Linksys router to allow command line access to the underlying Linux OS.

Bluetooth and IRDA are less common uses of wireless that let computers speak to phones and PDAs. I was completely unaware of the level of support that existed in Linux until after I read these chapters. While the Bluetooth coverage was comprehensive, it went to a deeper level of detail than I thought necessary, such as a detailed breakdown of the Bluetooth stack of protocols. However, at the end, it is possible to use Bluetooth and IRDA to pull data from devices, and to connect to their resources (ie modems and databases) over the air.

I should also mention the chapter on GPS. It is fairly thin on its own, but as an addition to the 802.11b section (ie wardriving), it does well.

A couple of things stood out about this book. The first is that the target audience isn’t necessarily Linux geeks, but Linux users. You don’t have to be a Linux guru to get this stuff running, the level of detail is sufficient to get anyone who isn’t scared of a command line up and running. The second is that the authors spent a lot of time testing various hardware. Many wireless cards and Linux distributions were tested in the early chapters. Where several options for software existed, they were all looked at (such as the source vs binary drivers mentioned above). This all adds to the book’s value not only as a howto manual for wireless, but also as a guide for navigating through product and software selection.

“Linux Unwired” is perfect for anyone who wants to use wireless on Linux, be it connecting to an 802.11b network, or trying to use a cell phone to send a fax. Those looking to purchase equipment will want to go through the book first to make use of the product advice and compatibility testing.

More information is available from the O’Reilly website at http://www.oreilly.com/catalog/lnxunwired/index.html which includes a sample of chapter 3, “Getting on the network”